Before I kept bees, had snakes for 28 years. had many copperheads. Are infact the least venomous of all the venomous snakes. in modern recorded medical history--NO PERSON EVER died directly from the bite of a copperhead's person. as for your dogs, of course I wish them well, suggest you keep them quiet, and well fed, keep them warm, and check for infection that's truly the killer in most snake bites. not the actual envenomation. If infection becomes apparent do not delay--bacterial infections can run away in animals as they seldom show the extent of infection until it is of alarming proportions. Again watch them closely, in the future teach them to stay from the little critters--believe it or not is a waste of venom for them to bite anything other then food--can't eat your dog and venom is a priceless item for them.
Barry